SEEDS Internship : Microfossils and isotopes: reconstructing common-era climate using lake sediments

The last millennium is an important interval for climate reconstruction because it marks the period during which human impact on climate has become increasingly important. Natural archives such as sediments provide valuable records of past climate. The aim of this project is to reconstruct climate from late Medieval times using oxygen-isotope analyses of calcareous microfossils from a pre-collected lake sediment core from Alresford, SE England. Oxygen isotope ratios from lake carbonate reflect past water isotope composition and temperature. Previous work at Alresford has shown that isotope records from different carbonate fractions can be used to track changes in seasonal climate. The project will involve processing of core sediment samples, extraction and cleaning of microfossils, stable isotope analyses using isotope-ratio mass spectrometry and quantitative analysis of data. Training will be provided for each stage of the process, and the intern will work alongside PhD students and researchers in UCL Geography but with opportunity to work independently of direct supervision. They will contribute to writing up the internship results along with existing data from the core. Much of the work will be lab-based (UCL Geography and UCL Earth Sciences) but arrangements will be made to visit the field site. Results from the project will contribute to the PAGES (Past Global Changes) 2k Network, an ongoing initiative studying past global changes of the last 2000 years. 

Work plan: Full-time

Week 1
Overview of work: Introduction to the project, project collaborators and others working on related research in the departments. Familiarisation with the sediment sequences and overview of the methods to be employed and the various lab facilities to be used
Experience and skills: networking with other researchers; introduction to lab methods including risk assessment
Week 2
Overview of work: training in, and undertaking of, sediment processing for microfossil extraction
Experience and skills: sediment processing; laboratory record-keeping
Weeks 3-4
Overview of work: extraction and cleaning of ostracod shells for stable-isotope analysis
Experience and skills: handling and identification of ostracod shells
Weeks 5-7
Overview of work: stable-isotope analysis of ostracod samples; comparison and evaluation of ostracod isotope data with existing data from fine-grained carbonates; preliminary plans for paper drafting and eventual incorporation of data into PAGES hydro2k database
Experience and skills: principles and practice of isotope-ratio mass spectrometry, including data processing, data visualisation and data-base contribution.
Field-site visit will be scheduled some time during the internship based on collaborators’ availability

Work plan: Part-time

Work-plan will follow the outline above but will involve working on 50-60 % of the total number of samples proposed for the full-time internship